It usually depends on where the sensor is mounted as to whether it is 2 or 4 wire. The 4 wire ones from VR onwards I think) were mounted further down the exhaust system (roughly near the transmission) and that is the reason they need to be heated, because they are too far away from the manifold to heat up quick enough. The 2 wire ones were used on the earlier V6's from about VN's to VP's (I think , but dont quote me on it) and were mounted in the manifold, where they heat up almost immediately on start up, being very close to the exhaust ports. Having said that though, I have a VR which has the earlier VN manifolds (done by me to overcome the cracking problem in the later VR cast manifolds) and all I did was extend the wires and put the original 4 wire one in the manifold. They are exactly the same thread and it wont hurt it, mine has run fine like that with no problems for over 12 months now. BUT BE WARNED, dont do it the other way around i.e. putting a VN 2 wire sensor into a VR exhaust system, because it will be too far away from the heat source, and cause cold starting problems and run poorly till it heats up. Hope this helps.
Stugdum
